Your Scientific Contact

Collembolan Field Study

A field study to assess effects and recovery on non-target soil arthropod communities

Non-target soil arthropods are important determinants for essential ecological functions of the agro-ecosystem like soil fertility and litter degradation. Applications of plant protection products should not significantly affect population development and community structure of soil arthropods like collembolans. A field study on collembolans under Good Agricultural Practice (GAP) is indicated if laboratory studies as well higher tier studies cannot sufficiently prove harmlessness of the plant protection product on non-target soil arthropods. The collembolan field study allows determining short and long term effects on soil arthropod communities and the potential for recovery.

Study Design

Tailor-made

Test Organisms

Collembolans, living in natural populations

Design of the Test Field

The collembolan field studies are conducted on grassland or arable fields. The test item (if desired with multiple rates), a water- or untreated control, and a toxic reference item (e.g. chlorpyrifos) are applied with at least four replicates on the test field according to GAP. All plots are arranged in a fully randomized design. The plot size is usually 100 m² (10m x 10m), but can vary depending on the study design. Distance between the plots is at least 3 m and approx. 10 m distance to the fields next to the test site.

Study Details

Collembolans are identified to suborder, family or species level depending on the study design. Other organisms like soil mites (e.g. Oribatida, Acari) or enchytraeids can be extracted and identified on request.

Application of Test Substances

The application procedure is conducted similar to agricultural practice. The time and frequency of applications follows the intended use of the product taking into account product persistence and possible interception by vegetation. The application of the test substances are carried out with a calibrated movable plot sprayer or granule applicator.

Analytical Verification of the Test Item Application

ibacon offers three methods for verfication:

analysis of spray liquid samples taken before test item application

determination of the a.i. content in soil samples

analysis of spray residues from Petri dishes placed on the test item treated plots during application

Sampling Methods

Collembolans are sampled with two different methods to cover collembolan populations from different ecological groups. Soil dwellers are extracted with a Mac Fayden heat extractor from soil cores. Usually six soil cores are taken per plot (euedaphic collembolans). Collembolans living in the litter- and top soil layer are caught with pitfall traps (epedaphic collembolans). Four traps are installed per plot.

Course of the Study

Collembolans are sampled before the application of the test item and usally four times after application. Plots are irrigated if the application of the test item is conducted during dry climatic conditions to ensure exposure of the soil arthropods to the test and reference item. Duration: 6 -12 months

Data Evaluation

Evaluation of the treatment effect is done by using Abbott’s formula for all representative taxa at each sampling instance. Statistical analysis on single taxa level is performed using univariate techniques. The effect of the test item on collembolans is statistically analyzed and compared with the control group for each sampling date. Control and reference item treatments are compared separately. Evaluation of the treatment effect on the arthropod community is done by using multivariate techniques and performing a principal response curve analysis (PRC).

Endpoints

The collembola field study accepts initial test item effects and usually focuses on the timespan which is necessary to demonstrate recovery. Recovery is considered to have occurred when soil organism numbers are not significantly lower than the control on two consecutive sampling occasions.

About ibacon

Since 1994 the chemical and pharmaceutical industries trust in ibacon as a reliable partner for contract research and efficient performance of GLP-compliant studies as part of their regulatory projects.